Map and method of making it



- May 4', 1926.-A

E, H.- coRLETT r AL ih? AND METHOD OF MAKING Ill'l'y Fiied sept. 5, 1922 .s sheets-sheet 1' vmul: mi 72 /A/vfzvmea: fowl/v H. Cnam 5 Sheetsf-Sheef. 2

f AF. /Y

May 4 1926.

E. H. eoRLE-rT r AL IAP Aun METHOD or' MAKING 1T `Filed sept.

May 4, 1926. 1,583,125

vE. H. CORLETT ET ALl IAP AND HETHOD 0F MAKING IT4 Filed Sept. 5, 1922 A EgSheets-Sheet 3 fa /X.

J gli' 'Planted May 4, 1926.

UNITED vs'rarlss EDWIN H. OBLETT, IAX. W. GABNETT, .AN D HOWARD I. DOREMUS, OF- EAS-T CLEVIEL .PAT-'ENT OFFICE.

LAND, omo. Y

m am) METHOD oF HAxIN IT.-

'Applioation led -Smptember To all /uihom t may concern:A

Be it known that we, EDWIN H. CoRLE'rr,

MAX W. GARNE'II, HowAnD'I. DornMUs, al14 citizens ofthe United States of America, all l residing at 1822- Marloes Ave., East Cleveland, in 'the county -o-f Cuyahoga and State of Ohio, haveinvented a new and useful Improvement in Maps and Method of Making. Them, of which the following is a specification, the principle o'f the invention being herein explained and the best mode in which we have contemplated applying thatprinciple, so as to distinguish it from-other inventions. L Our invention entitled. Map and method of making it pertainsA more particularly to employment of an aerophotograph or photographs disclosing the terrain or-portion of the earths surface ofwhich a ,topographical map is desired. 4

The object'of our invention is to'facilitate, expedite and cheapen the production I respectl thereto and of the scale desired for the map.

4Having anfaerophotograph, a plurality of identifiable feature points thereon (preferably four) are selected, then the location of said points relative'to each other and 'relative to a chosen datum plane is determined by standard ground survey practice, next we determine the average scale of the'pic-ll ture by platting on a blank sheet the four points to define a plane ligure ofthree or more sides and measuring .its sides', then we locate thel centerV of the 'picture assuming` 4said center to lie inthe axis of the aerocamera lens', and further transfer said center by ually markl an.

5, 1922. seriai No. 586,391.

approximate determination to said plat,`. measure the distances in inches from .the

determined center of the plat! to each of the- 1 four points, multiply each 'ofthe four-dis`` tancesby the difference between the elevations of theidatum plane and each particu- I lar one-of Athe four points respectivelyto plane figurefwas measured, divide each'of the fourI products by the product obtained by multiplying the scaleI of the picture and a number which is the foc'al length ofthe lens of the aero camera, said 'product being the altitude of the aero camera at the time of exposure, lay -ot' by measurement from the known center of the plat the four quotients so obtained having due 'regard to the algewhich the distance from the center of thev braio sign of each, correct the photograph or photographs by optical projection and rephotograph at an adjusted langular disposition of each 'original picture with respect .to the focal plane so as to eliminate elements of horizontal perspective by which we mean the. apparent perspective of lines on a horizontal plane as distinguished from llines in 4vertical planes, and incidentally enabling obtainmcnt of pictures uniform in scale excepting for possible rectilinear distortion,

grid the corrected photograph or photographs according vto coordinates, emphasize and describe the feature points and sketch the contours with respect thereto directlyv -tion of features on'thc surface of the earth by means of an aerophotograph thereof, in other words, using the disclosure of an aerophotograph for collecting data as to elevation of different portions -of the earths surface. The step of determining the elevations of prominent'features on the terrain by identifying' the Vlocation thereofaccording to photographic detail isthe primaryv useful conception which we hope to protect 'by patent. Subsidiary ideas are the eliminaltion of elements ofv perspective and effecting,

when a series of aerophotographs is employed, a general average of uniform scale thereof. If the photograph of the terrain S' which almost invariably involves elements of perspective is used `Without being first l corrected bythe elimination of horizontal pers ective, a topographical map; could be pro uced which would reveal .the mere existence of topographical det-ail, but not the exact scale location thereof. While correction for horizontal perspective could sub- `later be readily accomplished. If, however, theJ` areal of which a topographlcal map `is desired is' extensive enough to require av series of photographic picturesvthereof, and without a Willingness on the part of a customer to supportv the cost of a map requiring conformity with strict specifications, it woulldordinarily be preferable to lirst bring the'photographs to aiuniform scale.

Contrary togeneral opinion, an aerophotograph, even if taken mathematically vertically, is not a true plan. ADepending upon the use to which it may be put, it maybe called an approximation of a true plan. Until notice, inlthis dissertation it will be assumed that ltheaelo hoto was taken exactly vertically and t at, therefore, there vis no horizontal perspective therein. there beany relief o n the terrain, the vertical elements thereof will appear as real or imaginary lines on the aerophoto, all radial to the point on the terrain lying within theaxis of the lens of the aerocamera., If-J be the altitude of' the lens., above ay datum lplane of elevation and if be (considered algebraically) the difference in elevationbetween the datum plane and that of af point in relief (that is, the length of the-line from 'any point `perpendicularly :to Athe datum plane)','a'nd if b be the distance onthe aerophoto from the point -in the axis of the lens to the image of the point inv relief, then the actual displacement of the point radially,A or along a line which Yradiates fromlor passes through the nadir point on the terrian in a vertical optical axis of the aero-camera at the moment of 'exposure and lWhich-point may be lsaid to be the, vanishing point of vertical perspective. isa distance -which We '.shall vcall z.' Therefore :'-1'

of inches) and the correction to apply. in order to locate properly the point on' its radial line is A l hb y 2' and obviously the correction to apply to the platted position of the point to produce its .aerophotographic location is the same distance, but which when reckoned in a different formulawe call 2- so that v J h (la and J in feet; e and Z in inches), where d is the distance from the axial point to the platted (Orthographie) position ofthe point e in relief., If `the distances between the small crosses and circles in Figure III are considered as a then the same distances in Figure II should be considered as designated by z.

The above formulae are derived and mathematically proven iny the following manner:

Considering S as the nadir point, inan rssumed datum plane, of the 'center of the;

ens.

Considering U as'a point in the same datum plane and as the baseof the perpendicular line from the assumed point which is the .vertical distance l1, above the datum plane.

ConsideringI V as' a point in the datum plane which is' also in a straight line passing through the lens and through the point which is at the elevation h above the datum correctionfor the print. I v

.2l/d Y: "rdh/J-L which is the correction for-'the pla-t.

should be thesame,

the vscale of the aerophoto, whether it be a contact print or an enlargement ora-eduction; and, regardless of the focal y,length of the lens employed in makingthe'aerophoto.

It will be apparent from the above that the correction of any limited number .of points on an aerophoto is merely a matter of detail of more or less tediousness, but that the transferring of detail from an aerophoto to map paper in any quantity would' appear to entail an vimmense amount of Work. y

and a cost out of all proportion to thel value of the information gained. IVe Will l sl ow that a process has'been Worked out and 'put into lpractice commercially which enables one s illed: in the art, or generally technically proficient, to shorten and ch'eapen the making ofany type of general o r special mp' by using v aerophtographs.

ere are rtwo causes operating yto .pre-

vent an aerophoto positive (contact print or enlargement) from containing uniform scale in all directions. The first (in point of time in the process) is that it requires an appreciable time4 for the slit in the` focal plane shutter to travel across the film or plate; and in that time-the camera may have one or moreof several motions imparted to it. It will be travelling with the aeroplane; and it may berotating with a constant or a variable velocity about a line that may lie within the pla'ne of the film or plate, or. Without the plane of the filmer plate and parallel.

to it, or that may not be parallel to it and may or may not intersect the film orf-plate; and the line described may be rotating in any fixed or variable position about another line which itself may be travelling ina straight plane or a plane curved in two or three dimensions. In other words, the acroplane may be following any sort of a line, and the camera may be moving with respect tothe aeroplane.

(It is now assumed that the motion of the lslit is uniform-in fact it can be only approximately s ogand later we shall deal with this feature.) However, in the face of all these possibilities, one is safe in assuming that the only resultant distortion detectable will becaused, in most instances,'by the velocity'of the plane with rcspectvto the ground; and, in a few instances, by a slight angular motion of the plane, or possibly the camera,at the time of to 'be as fast as the focal-plane shutter.

The second cause producingscale distortion on the positive is the absence of uniform swelling or shrinking in photographic material. It is likely that glass plates and celluloid plates are so free of this feature of lack of uniformity as to be said to expand and shrink uniformly. Itl is further likely that glass plates expand so slightly that for map purposes they may be Acalled perfectly rigid surfaces. The gelatine may crawl uniformly or not. It is our belief that. for all4 time, this may be disregarded in mapping because distortion due to it is so slight. Photographic paper, requiring wetting in the process of obtaining .and fixing the image, will very probably always swell and shrink non-uniformly. The action, above described, of photographic materia-ls', will produce two component scales, subject to the-same basic restrictions as are the component scales resultlng from shutter distortion.- 'While shutter distortion, especially if it -be large, is troul'ilesome and difficult to correct, process or development distortion can easily be found and allowed for, it involving only a comparison between the same sheet before and after development. Finally, any scale distortion du'e to the shutter, and any due tov swell or shrink, combined maketwo component scales, either exactly or approximately at Now supposing the aerophoto has-been so taken that there are in its elements of horif zontal perspective-in other words, that the sensitized surface Was not parallel to the terrain when exposure was made. This means that the lens was not verticall'ypover the axial point 4on the terrain at'the timeof exposure. In a joint application for patent by E. H. Corlett vand M. lV. Garnett ,filed4 May 14, 1920, Serial Number 381,402, the four point principle and its application to this problem is thoroughly discussed; and 90 for di 'e1-ences in elevation on the controlin usino' that process, an accounting is made points. lVc, do not limit ourselves to the necessity of using fourpomts to determine the yscale of a picture merely because our drawings'disclose four points, and we used that in illustration of a practical method of effecting our system. W'e ,realize that, where' the accuracy of the finished map is of vless moment or where the skill inkeeping the camera level is greater, or both, there is presented the possibility offusing three,or or even two points to determine a scale acceptable vfor that of our datum plane, o'r as-I sumed, even, to be the scale of the picture as awhole. Also. we mean to cover the contouring of 'uncorrected photographs, prior' to, during, or after the determination of scale, by a determination of the spatial relations of a plurality of identifiable points on cach ofthe photographs involved. Briefly, four points, identifiable Ion the aerophof' tograph (preferably, points which are," for economy, on one or more adjoining photo-- graphs) are chosen by` the chiefof the survey party Aas tie lpoints for his survey. These points are located and elevations noted thereto by anyone'of various methods in current use in survey practice. Then, a sheet is prepared with t ese points platted thereon, preferably to.l the scale of -the finished map. From these points, and the points yon the contact print, a comparison is made which permits the calculation of Ra very rough scale, regardless of elevation, of

the print (or negativeitis generall Vimf lresults). Itis temporarily assumed that the center -of the print is the image of the -axial point and the image of the. point vertil cally below the camera onrtheterrain; and

material, though the negative gives etter f a seriesof short approximations and corn `parisons will locate, on the plat, approxiaerophoto, together with personal knowledge of the terrain bythe person making t-he survey, determines the elevation of aplane that will most -nearly approximate the 'elevation of that portion of the terrain which is most likely to be of interest to the user of the aeromap. The elevation of the control points being known, the correction according to the third equation earlier furnished is applied, giving vto'scale the position of the control points for that particular aerophoto, when relief is taken into account. Obviously, while 'the platted location of any one control point to coordinates according to survey, will be the same for two overlapping aerophotos, the position corrected for relief can not be the same, expressed in coordinates, -unless the `control point lies Ion a straight line connecting the Verticalpointsfand unless the elevation of the points is the) means of .the `elevations of-the two datum planes. This is merely a mathematical way of statingthat,

regardless of anything that can be-'done to.l the elements of a mosaic, relief in theL terrain precludes any possibilitv of universally matching the elementsfinevery detail-'in `fact, they can be matched only .on points that lie in a horizontal plane common to all the aerophotos of the set, excepting under the condition above laid down (in being assumed that'aerophotos'are placed according to survey and not juggled slightly to proand . of expansionof the enlargement paper liefore the true P and Q' are looked up.

This operation is followed for the required number of aerophotos. lfVhen .the data is collected, the negatives, one after another, are loaded 4into the machine, the required. setting made for each, and each is exposed. The result is aset of enlarge:

. ments, all .to a fairly' .uniform scale, con- `taining (.assuming no error in survey or in y carryingout the above desc ibed process) no variation in scale, on any one enlargement. However, several vthings may happen. If theratio of enlargement' is considerably duce an appearance of approximately matching). Then the controlpoints, in theiry corrected positions, constitute lthe four points in the patent application of Corlett and, Garnett. 'j

^ Of the several method described therein for effecting perspective correction,`the one actually in use is that involving a lens of a focal length such that its position with re.-

spect tof the negative. in the projection machine is approximately the same as the po.

sition f the aerocamera lens with respect to the negatlve at instant of exposure. The

plat is mounted on thetipping easelj and l the latter is manipulated until coincidence of the four control points with'the ro.'e,c-

eit ertionsof the four indentiliable points from the negative or from a hand copy therefrom) is' effected. Then the positions of the lens with respect to the negative and the fixed' points easel are noted, together' with tip and turn ofthe movable easel".

its horizontal turning and its vertical tipl ping. Thelens observationstake the followinfr form: y

,s Q,zdistance from lens to pro]ected 1mage recordmg surface. f

F=focal length.

.P zobserved distance lens to negative (or toy sheet withtranscribed points. used in place of negative.)

D =observed distance negative (or sheet, etc.) to the fixed point of the easel.l I

TC- observed rotation about vertical axis of easel. I

Bzobserved rotation about horizontal axis of easeh Then, i

D, P, Q g (Standard formula: P12

=ratio of enlargement, as observedp different from that used in determining the lens for the process, a square on the ground y.( according to the joint application Corlett'- Garnett) will be corrected into a rectangle;

of the distortions.. In-adjust-ingour enlargements for elimination of perspective, we vmake nodistmc'tion between these fac- -and if there is any appreciable shutter distors. I fjwe cannot obtain a perfect coinfl cidence, we try to obtain an adjustment of a nature such that proportional. change of ldimensionl of the lprojected vimage along a set of parallel lines (which we do not yet produce by optical apparatus) would give us coincidence. This means that, on, the pro- I. projection board.)

f-jectionf-bcard (easel) and independent of other causes, We have two component scales.- (The difference in these 'two component scales seldom is other thanhegligible, on the Then there is ,another point and assumed to be approximately'coincident with the point vertically under the camera 4at the instant yof exposure. (It is to be understood that the last mentioned point. -is not a true point,oas theplane is lnioving-but,A consistent with our other `as sumptions, anything that will come Within y the method of making contour maps will `the limits of scalingis a close enough afpproximation of the mathematically correct quantity or representation.) When a line through the lens and perpendicular to the displaced leasel gives usfa point on the plat through which We may drawjradial correction line-s' that Will, with the application of the third' equation, give us the bestvpossible approximation of superimposition (bearing in mind the distortion likely to be produced las described'in the first part of this paragraph) of projected points on to the corrected location of theplatt'ed control points,

- an unusual tip of the raeroplane or camera is thereby registered. y

When the enlargement is dried, itis ready for lone of tivo things: incorporation into a mosaic or use as a location sheet in obtaining other field information and in making any other sort of a map, even a contour map.

Vvhen used in a mosaic, it mayrequire exlposing for more than one datum plane and piecing-together in any way that Will best 49 convey the desired information; If the compcnent scales are tdowidely divergent, it will necessitate.makingl the enlargement so l that its minimum-scale equals the scale of the map, and cutting often'across the dimen-y 5 sionof the maximum scale and lap-ping, so A that no importantdetail will be'missed.

This Waythe Ioverlap scale will be correct, and the error in short.l lengths Vdue to the v difference of the maximum component from 5 the map scale will be'negligible.

lfVhere. the enlargement is to be used ias the basis for other WorkV toward the production of a drafted map, the procedure is as fcllowsz l The enlargement, either'mounted or unmounted, is gridded. This is done by bringtangles), all the scale work up to this point has been correct-survey, choice'of points, plat correction previous to using in 'Corlett- Garnett machine, perspective adjustment, adjustment observations, actual process of enlargement, and gridding. If 1 the grid figures are rectangles, it means that the componentscales happen to coincide with the' directions\\chosen for grid lines (generally NS and EVV).\' Ifthe figures are squares, it'

means lthat the sum of all the errors is zero, excepting that the ratio of4 enlargement may\ have been figured wrongly, or used O'ly. This last is not important, as transference is mainly .by pantograph.

It Will be assumedthat a description of cover the making of all other forms of scale terrain maps. The" ridded enlargement is taken into the field gy4 a party made up. of two or more men, equipped with a plane table (minusalidade), a level, a rod, a hand level and customary incidentale of topouraphic surveying. (It must be remembered that one man could Het topography with the enlargements provrded he could find a reliable means of obtaining elevations. theoretically perfect barometer would siver. We detail ay method found practical.) It is n'otnecessary to detail the rout-ine of contour location on the ground-that is standard practice with infinite variations. The variation from previous practice comes lwith the almost entire elimination ofhoricontour is located, sometimes controlling elevations are located and contours are interpolated-there is nothing new .about this other' than'recognition of the contour and contourers locations via photographic detail. 'lhe elevations, with our system, are

an-...f

obtained bydirect levels.- They could be 5 obtained by any. economical and correct method? The f contours are 'placed on the enlargements according to photographedmentis pantographed onto the map sheet.V

In order to do th1s, 'it is necessary that We know the scale of the enlargement as ,a Whole,

or part by part, in case there seems to have been trouble anywhere in the processes up; to this stage. I f the gridfgure's are'` rectangles, a simple lscaling will glve ,the compowit out letting in any errorof a destrucnent scales. If the angles'are appreciably different from v90", the components scales caribe found as follows: Considering any one grid ligure We locate 'on the perimeter of it, by purely geometrical means, enough points so that lines through these ioints and (preferably) the center of the ligure will 'give radial lines at about every 20 or 30 of the circle. Locate the corresponding geometrical points on a Standard square grid ligure. Determine the scales along the radial lines in the skewed figure. Plat a c'urve of arithmetical differences of these scales from the standard as ordinatcsand with azimuths (and their supplements) as abscissas. A harmonic or sine curve can be ldrawn as a mean to the plattcd oints. If'

thc crests are lSOOi apart; and,tie troughs,

vazimuths of each. These are noted on the l enlargement; Ido not limit myself to the method outlined above as I am aware that other methods canbe used to deter ne the maximum and minimum scales. n our practice, it is seldom necessary to do this, as the variation from 90 of the grid figures is seldom of an amount sufficient to prevent the use of the figures as they are, within any' reasonable limit of error for a scalemap. (In any case, the map as a whole will be a's lgood as the control survey-or the data use-d as controls-and no one can except to scale very small distances within a great degree of accuracy.) l yThe grids aslaid out, according to previous description, are .true to photo-scale only upon a certain datum yplane.: All contours, features--ni'ap data in general-on o r nearly on that plane are transferred, accordingto that scale, the setting of the Ipantograph having been. determined therefrom.`

Then, using the equation number (V2), a -new set of grids is penciled on the photo (genv erally only at intersections). For the lower elevations, the grids on -the enlargement will'- obviously have a smaller scaleand for the higher, a largerscale. AThis is because' high ground is the nearer to the aerocamera. As

these corrections are Ymostly always of the l order of less than 0.05 per single adjust'- ment, the `breaks in continuity'in the map as autographed can beI eased in free hand l -tively largequantity. This process is 'followed; en argement' by enlargement, to the' l. completion of the pencillingl of] the; inap.

ldirect contact printing.

When `desired this map can be inked or traced in any well known manner. Such is the process as at present constituted. It is 'theoretically and practically correct (within the limits of standard map accuracyand according to various qualifications mentioned as possible divergencies of ood-enough ractice from exact tlieor Wherever there is any doubt as to the location of a grid line, rather than to determine it, in the field and otiice, we rely upon comparisonsl with adjacent pictures. Pantogi'aphing does not proceed until there is coincidence of grids, enlargement to enlarge'- ment, with due allowance made for what difference there may be,if any, in the elevations ofthe datum plane of the one en-l largementand that of the second., "In this whole matter, the following arc new features:v i f A. A method for applying relief correction to aerophotos and` to data obtained therefrom, based upon the altitude of Hight and the approximate location of thepoint vertically under the camera at time of exosure within the limits of accuracy imposed A y the users^of scale maps.

B. A method of correcting horizontal perspective as described in Corlett-Garnett application,

' b. VVhereltlie relief is considerable, A minst be applied in preparingjto use B.

C. A method of locating contours upon paper'n the field, involvingl the identifiability ofv locations in most places by inspection of an aerophotographic product, either a contact print or a projection, .or an enlargement. (We have used the term en-f largement` herel referring to .any photographic print made by rojectioii lustead .of

D. A pantograpli embodying several new and -cheapening features. y l

E. A chart to enable the user to set the pantograph so that it will,I within practical 1imits,'transfer dataon two different scales to a drawing of one unifornpscale, i. e.:

bring an ellipse to a circleaccording to any previous intent."

F. A method for determining the amounts l and azimutlis, of maximumn and minimum scales 1n a 'parallelogram compared -to a standard square.

G. Av method,derived from A, ol. proy ducing an Orthographie contour map from an aerophotographic p roductwhich has been contoured and filled withl information in the eld. f

. General-summary: a process-for gathering field information, using acrophoto products;

and a process' for trans erring such iii-forma j tion to a drafted map and in such process,

a method for.` eliminating errorl dueto shutter distortlon, to uneven material "expansion, slight discrepancies in survey and for eliminatlng vertical as well as horizontal perspective; 'the whole shortening and cheapening the production of eatujre and topographic--in general, scale,maps.

- Adverting to the drawings Figure I 1s a faeslmlle reproduction of the essential features of a terrain photograph (contact print) as initially obtainedwitlr elements of perspective, with the location of survey control points indicated thereon,`

Figure II shows a. sheet of coordinate paper with a plurality of control points plotted thereon.

Figure III is an enlarged copy of the lphotograph shown in Figure I though additionally vcorrected so as to have no horizontal perspective but possibly rectilinear distortion and sup lied with grids corresponding to' those s own in Figure II, the data in the Lindicated rectangle having been obtained from an aerophoto.

Figure IV portrays an irregular quadrilateral iigure'as an exaggerated illustration of the diiiiculty experienced due to rectilinear distortion. Such a ligure is to becor'- rected into a square.

Figure V isj he equivalent square of Figure IV.

Figure VI shows a curve plotted to efect the determination of the magnitude-s| and azimuths of maximum and minimum scales.v

Figure VII is a diagrammatic View ot la p antograph provided with our adjustable connections. v

Figure VIII is a detail view showing the manner of effecting adjustment on the-left.

,side of the pantographshown in Figure VII.

Figure IX is a detail view showing the manner of effecting alining adjustment on the right side of the pantograph'.

Figure X is abottom plan View of Figure IX. -f

Figure XI is a reproduction in effect of a chart to be used with the pantograph for the purpose ofdetermining certain values.

Figure XII is a broken section ofI the l yfinished map.

In order the better to emphasize the salient features of our invention, the provcedure will be detailed. Figure I shows a contact print of a negative made by an aerocamera. Thereon are shown a'wooded valley,' '2, a barn, 3, a house, 4,'an unmproved road, 5. a paved highway, 6, a

farm road, 7 ,a rail fence. 8, and other data,

nearly all of which is recognizable by inspection. In this lparticular case,.we will assume that a traverse is run along the highway, 6. From this traverse, ties are made to features identifiable on the print, and vin the `Ideally,T 'ef course, -0f the area' -covere general vicinity of -the diagonals thereof. goints at the very corners .by the'print. 1, would .best serve theypurpose; practice, however,

is an approximation. to this conception. In

this case, the ties are made to a fence'. corner 9, the end of the l'ridge .of a barn roof 10, the-corner of a barn 11, and the end of a head `wall of a culvert 12. In the notes of the survey, and henceforth in the drawings and-in this description of the method, these points are numbered 163, 164, 166 and 165 respectively. Elevations of these 4points are determined coinciden-tally with their horizontal locations and pn Figure. II, are"marked as 58.5, 750, '650 and -510 feet respectively. In F igure II, a sheet of paper 13 is vshown with the locations of the cont-rol points (163,-

164, 165 and 166) platte'd thereon as indicated.

l.In vour process we plat by coordinates,

though thatis immaterial.A Coordinates are shown thereon, as also arethe designations and elevations of the control points. The center 14 of the print 1, Figure I, is determined by the intersection of diagonale.` By

comparison and measurement, this center is transferred to the plat, 13. Because the/ap;

.parent p-ositions ot the control points onthe print 1 are not their true positions withrespect to each other (due to Ihorizontal perspective, relief, shutterdistortion, paper ex'- pansion, etc.)l the exact locationl of the center 1.5 on the plat; 1.3 cannot be made. However, the approximation reached is close enough in most cases. 'l'hc case where it will not 'l -serve has been previously discussed. On Figure II thelittle circles are the pho- .tion'will be between the trnepoint and the center. In passing, we remark that the picture center is assumed to be both the point on the axis of thelensand the point vertically below the camera at' the` instant of exposure.

Points 164. and 166, on the lplat- 13, Figure II, however, are higherth'an the datum plane 4therefore their photographic locations will be outside their true locations; lVithin the limits of scale location, a ,radial .o li'set dependsl directly ,uponfvariation 1ot' elevation from that ofthe datum plane and upon the location of the lcontrol point "wit-hrespect to theJ center, and depends inversely 'i upon the altitude of thedc'amera above thcdatum plane. Whether the o'sets are made .toward or away from` the center depends upon -whether thegpointvisbelow or` above the datum plane We will assume here that fil' ' tice.

' the camera was twenty-four hundred feetA (2400) above the datum plane, then the offset z, is found thus q radius 16 xrelief (7 50-585) If 16 is in inches and relief argl 2400 are in feet,.,thenA z comes out in inches and fractions thereof.

The control sheet 13,'as We call it, i'sthen used according'to the Corlett-Garnett process, as disclosed in their joint invention, to

' produce the corrected projectionprint 18, in

Figure III. -It mustxbe remembered that the circles, 9,-10, 11 and 12 representing the photographic vrec-'o ldations of the control A, points, 163 to 166,' on Vthe print 18, Figure II, correspond to the encircled offset points 163 to 166 on 13, FigureL II.

The'projection print 18, does not'require gridding prior to field use, but it is handy to have it gridded, because itaids in orientation, calculation of acreage covered etc Therefore, fromlthe photographic position of the control pointson the print 18, the true positions are laid off, either by formula or by transference ,of-the offset from the plat 13, Figure II. It is extremely unlikely that the correctedpoints on' the print 18 will su- III. .The gures obtained maybe anything except squares, though'if the controll survey has been "correct, the latting andoffsetting correc-t,the .Corlettarnett process correct, y and the expansion orshrinkage ofthe-projection print -uniform as' mentioned, andthe grid platting has been correct, the figures will .be parallelograms. Obviously, if the camera were tilted fat exposure, it is almost uniform with respect to the terrain. -I-Iowever, such varlationfrom uniformlty 1s .negf ligible; and, aswe sald'before, there 1s no shutter ,distortion with a between-the-lensr shutter. The eiiect of shutter distortion on grid figures has been vnegligible in our prac- TheA projection terrain represente therein; and contours' as l perimpose upon the platted points on the plat .13, because itis probable' that the projectioninconceivable that shutter distortion will be an elevation of 610 feet. Then itis a simple matter to sketch in contour 600A with respect to 19 and 20. Fence corner 21 may have an elevation of 648, andthe ground have a slope of such a nature that a two foot rise to contour 650 will indicate a certain distance lin-a certain direction. This process is repeated until the data desired has been Y collected. In addition to contours, the na- .tu're of fences, the dimensions of structures, the` nature vof geological features and ot vegetation may be noted, as -also the proper outlines of objects identifiable in the field but not in .the ofice. It must -be borne in kmind that the photograph shows a great deal more data than can be shown on a drawing; where .identifiable objects cannot be found to enable the jsketcher to locate properly 'the contours or other' conventions of`4 information;

1We will assume that a grid figure,has a shape and size vlike Athe parallelo ram 22 in Figure IV. In order to obtain t emagnitudes and the azimuths of the maximumand minimum scales we compare it to a true square 23 of the scale desired on the finished map, as appears in Figure V. Pointson the' perimeter of the square 23 are 'laid out geometrical1y,so that corresponding points' so that there are no large areas These variations and the tilinear coordinates (any system would cio-- Arectilinear is handiest). See Figures VI. A curve 26 is. sketched into approxlmate the platted points. lThen 26 and 27 are the points on the curve 25 that give magmtudes minimum andl azimuths of maximum and scale ratios-respectively; Laid out on the parallelogram 22, Figure IV, are the maximum scale ratio 28 and the minimum scale fratio 29. a

Our pantograph, shown"A in Figure VII, whenset up`,'is placed to function according to the maximum and minimum axes, determined as heretofore `described.' It inpivot O. Opposite4 ends A and B of the beam articulate with rods R and R which may-vary. in length. A bar r3 likewise articulates with the rods, R and R at C and cludes affixed length; beam including sec-'- tions 'r'. 'and-1'2 .on-opposite sides of a fixedv l required,- exemplified 'by 450, 500,550, .600,

- ""'coordination` of, data, Qbtainedvby any sur- 6 ,base-.of say, atree219, Fi f e'rIII-:has an I a 20h t1on offreeordmg pencil T along'lme' -7 D respectively and inA a parallel relationship (Q') ,650. and 700, are drawn in according tothe' With respect tothe beam.

i ,The length of R;1s'generallytaken as fixed, with us, 19.00. R is varied. .WithyVey method, as toeleva-tio'n, with dataob.- o

1n a short distance of thelr respective origins,

tained aerophotographically, as'to horizontal location.. `In vthe eld we find that the Rwill produce very close to rectlhnear mo- *5 elevational? 597 faawd t.

motion in the directionof line XX of tracer .4 f

X', the amount of the motion being very close dto proportional to the lengths of R. and R. 1'2-l-r isv a constant, with u's, twenty-four inches. Within a short distance of their respective origins, motion of R in l'direction of line Y-Y will produce very. close to rectilinear motion of T along line.

of proper map making. This is because ,the

difference in the component scales is never` so' great as to strain the capacity of the contrivance or the elasticity of theproccss.

The only precaution necessary is that the operatorA of the pantograph mustl 'exercise caution and not attempt to go too far be yond the origin he selects if there be great divergence between his maximum and minimum sca-les.

A-B-CfD is the controlling arallelo- Oram of the pantograph. At A, C, and I) are hinges, the :hinge pins being taper mandrels, each fitted to its respective location. All wear is therefore easy to take up; and the machine is very easily dismantled. The figure A-B-.C--D is brought to be ya parallelogram b actual test'of'its .per-- formance rather tian by Lmeasurement between hinge pins. The'bar G--D is adjustable in length Vby shifting bolts 1'* in slots fri;- and` the length A-C is adjustable-via bell crank lever c and screw c2. Furthermore, there is an adjustment at D by means of'screw d and spring d to insure, by a simpletest that T is on D-B produced. This'testis to set the pantograph vfor true rectilinear motion and make the adjustment at D until Re the pivot axis O, and' T are on the samestraight line. What happens here is that D-B-*T may be on a straight line while D- B-F are not;.or '--C-R may not be ona straight line, but. as`long asl A-B-C--D .is 'a parallelogram, and

R-O--T are brought in to a straight line,

any other flaw of the machinery lis negligible altogether. This has been explainedbecause, with the provisions noted, this pantograph Will do all any pantograph will do, for ac curaey; and it can be built v ery muchcheaper than the so-called precision pantograph. To instance the manner of use ofthepanl; tograph after having determined the proper ratios and considering thel squarel shown 1n Figures II. and III as bounded at the top by the coordinate line 200.000, at the-bottom by the coordinate line 199.000, at the left by .the

coordinate line 266.000 and at the right by the coordinate line 267.000, and supposing both the upper and lower boundary lines` of the particular grid square to measure 5.05 .whereas itv should measure 5.00 and supposing further that the two lateral boundary lines each measure 4.95 instead of 5.00 as they should, the'user will refer to the diagonal grid dimension shown in Figure XI, will locate the point 4.95 thereonand from it will glance down along a straight line of vision to the bottom to obtain the value 12.04 as the setting for r'f and similarly will locate on the diagonal grid line a point 5.05 and then glance to the left along a4 straight line of vision commenc ing at such point to obtain 19.2 as the setting for R (see Figs. VII and VIII) to obtain the required factors. Therefore, by making the proper adjustment along R and movingv the point R from the lower left hand corner of the selected and identified -grid square to v-the lower right hand corner thereof, the distance 5.05v may be reduced to the distance 5.00 as translated and recorded b the pencil p-oint at T. Similarly after esta lishing the proper setting-,along the graduations on r2 and moving the pointR. from the lower left f hand corner of the selected and identified coordinate or grid square to the upper left hand corner thereof, the distance 4.95 is increased to 5.00 by the range of movement imparted to the point T. The ratio desired between distances lying in the aXis'lX-X to distances lying in the axis X-X c an be obtained by a setting to suitl along the grad- 'uationson the R scale. The ratio desired between distances lying in the'axis Y-Y to distances lying in the axis Y--Y can be obtained by a setting along the graduations composing the r2 scale.' It should be understood that the point R is the'tracer movable according to its predetermined secured position along the scale R while T denotes the recording v neil.

On one c art as shown 1n Figure XL-we arel able .to determine thefollowing from "the distance in inches along a grid igureside (we use 1000 foot grids); the scale on the Y enlarge-ment and the settlng for the distance R or r2, as the case may be. Then, we use common pantographingpractice for setting` up to transfer,provided that- Y-Ylan X -X correspond substantially to the azimuths of the components of the scalesfo-f the aerophoto. l .f The'coordinates as laid out on the print 18 apply only to -the datum plane. .For4

terrain above the datum, `the figures above will be larger; below, smaller. Each grid `intersection for any particular plane rabove or belowthe datum is determined as were the offsetsv of the control points on the'- plat 13,

Figure II. For instance, refer to 3 0 andlA to see -treatment of grid ligure to makeit apply to terrain belowdatum plane and see 32 and 33 for treatment of grid figure-to made it apply to terrain above datum plane.- In each case' a fi refsillilar'to the original grid figure' is .o tained, for lower planes, smaller andl displaced radlally toward the center; forhigher planes, largegand displaced radially away from the center. (It

Y is to' be understood that center as used implies that the center of the picture is'within reasonable limits, coincident with the point on the terrain. vertically below the camera at the moment of exposure and also with the point on thev terrain lying within the axis of the lens at exposure. When the Corlett-Garnett method has determined that the center is substantially removed from the pointvvertically `below the camera atexposure, such point -is approximately located; and ,is then used throughout the process in place of the center.')" The data within A4 B* C* D4, Figure III, ispantographed to the grid, square whose north east corner is .2660()0- 199000 on the'map paper. Similarv1y, the data within EFGI-'Ibis tranferred to id `square whose north east corner is 267000T201000. In practice, a series of imaginary grids are used, taken often enough' so that the sequence of transferred data from low ground to highground is substantially smooth.. The joining of pantographed data, from one plane to another, is done free hand. Figure XII shows a section of the finished map, with K LMN outlining. the

area covered by the aeroph-oto the treatment of which we have followed. 34, 35 and 36 are different sorts of fences, 37 and 38 are barns while 39 is a house. The other data y .are amply intelligible,

scale maps. Naturally, this also applies to corrected mosaics, because, given the elevations of any set ofvpoints and the elevation of a datum plane upon which 4the scale is known, the positions of these points can be reduced from photographic to real, with respect Ato each other, within the limits imposed, for accuracy upon a scale map. It is also feasible to compare photographic location of an object" in relief, that is, above or below v4an assumed datum, as shown on more than one aerophoto, and todeduce from suchcomparison the horizontal location of the object with respect lto anylines of reference upon the datum plane. 'Its vertical location is also deducible-from` such data. Our methods control all the data of the aerol photo to the accuracy of the control survey.

' 1. The method' of making a topographical map which consists in contouring aerophotographs, and thentracing each contouren a ratio according to its elevationl with respect to a chosen datum plane of the `photographs. y A

v2. The method of making :a'topographical 'map which consists in-contouring in the field enlargements of terrain photographs taken at a high altitude, and then tracing eachcontour on an increasing or decreasing ratio according yas its elevation was abve or -below a chosen datum plane of 'the adjusted photographs.`

3. The method of making a topographical map which consists in shifting map points. of aero-'photographs so that their features will be correct to` scale on one plane, then contouring said corrected photographs and finally tracing each contour on a ratio ac-4 cording toits elevation with respect to a chosen datum plane of the corrected photo-` graphs.

4. The method of making a-topographical map which consists in making a n aero photograph, selecting a plurality of\ points, ,determining by ground survey the location of said lpoints .relative vto each other and relative toa chosen horizontal plane, determining the scale of the picture, locating the center of said picture, transferring said points, transferring such center to its proper place between said selected points, scaling the distances from the determined center to each of the points, multiplying each distance vby the different between the-elevations of the datum plane and the particular one of the points respectivel dividingleachof the several products by t e roduct obtained by multiplying the scale ofJ the picture and a predeterminable number, laying ofi' the'quotients so obtained by measurement from the center of the selected points, correcting the photograph by optical projection to elim- 'no inate elements of perspective and obtain a picturwe true to scale, coordinating the picture into sections, sketching directly on the photograph thefeature points andcontours A and finally transferring onto map paper.

5. The 'method of making a topographical map which Jconsists in '-taking an` overlapping series of aero photographs, selectingv four feature points, determining by standard surve)7 practice y-theA location of said pointsrelative to each other and relative to a chosen horizontal or datum plane, determining the scale of the picture including the step of platting the poi-nts, locating the center of said picture, transferring such centerto lts proper place between said four selected points, scaling t distances from the determlnedcenter to each of the four voints, multiplying each distance by the di erence between the' elevations of the datum plane and each one of the four points respectively, dividing each of the four products by the product obtained by multiplying the scale of the picture and a number determined by the -altitude at Which the aerophotographs were taken, lay off the vfour quotients so obtainedA ing the pictures into squares, Ysketching directly onv the photographs the feature points and contours and finally pantographing desired map points and topographical designations of -all the photographs as `a continuous series onto map paper to obtain the proper uniform scale.

6. The method of making a topographical inap which consists in taking an overlapping series of aerophotographs, enlarging them, selecting atl least four feature points, determining the location of said points relative to each other and relative to a chosen horizontal or datum plane, determining the scale of the picture including the step of platting the four points to give a plane geometric figure to be used as a plat measuring the sides of such plane figure, locating the center of said picture, transferring such center to said geometric figure, scaling the distances from the center of the geometric figure to each of the four points, multiply-` ing each distance by the difference between the elevations of the datum plane and each particular one of the four points respectively to which the distance from the center ofthe plat was measured, dividing each of the four products by the product obtained by multiplying the scale of the picture and a number, laying off by measurement from the center of the geometric figure the four quotients so obtained, correcting the photographs by optical projection to eliminate elements of perspective and obtain a picfture true to scale. coordinating the picture into sections, sketching directly on the enlarged photographs the feature points andcontours and finally pantographing the desired data of all the photographs as a continuous series onto map'paper to obtain the proper uniform scale.

,7. T he method of making a topographical map-Which consists in identifying features o n a portlon of the terrain `by reference to a single photograph thereof, contcuring said photograph and finally transferring Amap points ldenoting said features to map paper according to their real relative-locations. i

8. The method of making a topographical map with the aid ofan aerophotograph of the terrain of'which -a map is desired, which consists in eliminatingV from said photograph elements of perspective due to terrain relief, including'the step ofascertaining the elevation of features common to the said photograph and to the actual groundv comprehended thereby, the step offascertaining the photographical displacement of said features and the step of-drafting survey designationsdenoting said` featui'es in their true relative'positions.

9. The niethodvof making a topographical termining` the elevation of featurescommon to the actual ground and to said photograph, then sketching on said photograph topographical designations of said features inap which consists -in eliminating elements of perspective in anaerialphotograph, de-

in. their apparent relative positions 'and finally shifting someof the relative positions of somel of said designations by recording theni ona separate sheetaccording to 'their known elevations;

10. The method of making a topographical inap wliiehiconsists in taking an aerophotograph of a certain area of the earth-S sui-face, eliminating any existing distor/ tioii diie to non-parallelism of the camera lens with relation tothe earths surface at the nioiiient of exposure, observing and re'- cerdingthe apparent relative locations, by measurement and notation," of features of4 a topographical character and then effecting adjustment to bringvsaid features to a uniform' Vscale and transferring to a separate sheet.

11. The method of making a topograpliical map which con/sistsin taking an aerophotograph of a certain area ofthe earths surfaceeliminating perspectivedue to nonparallelism of the optical plane of thetaking lens with relationjto the-earths surface at the moment of-exposure,` measuring and re- -cording the apparent yrelative locations of features ofv a topographicalcharacter and then adj ust-iiig the relative positions of said features tov their ascertained'true and proper relationship and pantographically transferring them to different material according to the predetermined ratios required.

v12. A photographic inap having marked thereon a pluralityr of control points andI a plurality of coordinate lines having a 'definite relation to said control points,` f

`13. A map comprising a corrected aero- -photograph having marked thereon a. lurality of control points and also a plura ity o1 coordinate lines the position of which is dei termined according to of `said control points.

14.-. Aunap comprising a photograph. of

the relative position an area of the surface of the earth. said.

photograph -being'of uniform scale with reference to a. chosen datum plan'e and having marked Vthereon a plurality of control points and a plurality of coordinatelines the rela'- tion of which 1s determined'according to the ascertained elevation of l,said control points with reference to' the same datum plane.

15. A map eomprisin aphotograph of an area of the surfaeeof t e earth, said photograph being of uniform scale with reference to an assumed datum plane, having platted thereon four control points and having also marked thereon a plurality of coordinate lines the disposition ,of which .is determined according to the ascertained relative elevation of said 'four control points with reference to the assumedfdatum plane and the sizeof the squares defined thereby varying according to the elevation of the assumed datum plane. y

16. A 'method of making a topographical map which consists in obtaining an aerophotograph of the area to be mapped, -locatlng and recording data concerninor physical features of said n rca by direct oiserv-ation thereof and'by visual reference to feature points disclosedl on said photograph, and

' then correctly drawing survey designations denoting said physical features in relative Ipositions determined bv a uniform scale. t

17. A method of making a topographical map U which' consists in` obtaining an aerophotograph of the area to be mapped determil'iing the apparent locations of physical features by visual reference to their feature points as disclosed on said photograph, de.

termining the (true relative locations and elevations of said physical features, and then' then pantographing on map material topographical designations denoting said physical features as map points according to their calculated displacement caused by elements photograph due to ter-- of perspective in the rain relief. c

19. The method of making a topographical map which consistsv in making an aerophotograph, selecting aplurality of points, determining by ground survey the location of saidpoints relative to each other and relative to'a chosen horizontal plane, determin-y ing the scale of the picture, calculating the relative location of 'said points according to their ascertained elevation with reference to 'essaies 20. The method of making `a topographical map which consists in sketching contour designations on an aerophotograph according to observation and' measurement in the field, and then transferring toa distinct sheet the topographical designation of each contour on a ratio according to its elevation components with respect to a chosen datum plane. l

`2l. A photographic map having contour indicia directly traced thereon.

22. Av corrected photograph of the earths surface having directly traced thereon standard designations denoting existing topographical featnres not otherwise apparent;

23. A combined photographical l topographical map.

24. The art of making a topographical map which consists in determining'the relative elevations of physical features spread over a given 'area by identifying said features, and thereafter both measuring and recording the vertical components of their locations on an aerophotograph.

25. The art of making a topographical map whichl consists in correcting an aerophotograph by eliminating distortion due to perspective, determining by field observation the elevations of physical features spread over a given area and then recording on said aero-photograph the locations of said features i shifted to relative positions as though all were of like elevation.

26. The method of makingI a topographical map which consists in takingan aerophotograph of the territory, locating and marking on the photograph observed topographical data and finally transferring the data to map material,

27. The method of making a topographical map which includes the steps of locating oneself at the place of which a mapis desired and then observing andrecording topographical data, all by reference to an aerophotograph of the terrain tobe mapped and then drafting a map by reference botli to the photograph and to the recorded data.

28. The improved method of making a topographical map which consists in ytaking an aero-photograph to its disclosed area, measuring horizontally and vertically observed physical features, sketching on the photogi aph topographical designations'with relation tofeat-urepoints thereon and-then drafting a map from the data'thus collected. f

29. The improved method of making a nasales topographical map which consists' in taking an aero-photograph to its disclosed area, determining the relative spatial location of obs served physical features and then sketching on the photograph contour lines in correct relationship to feature'points which appear on the photograph. i 30. The improved method of making a topographical map that consists in procuring an aero-photograph of the area intended to Vbe mapped, correcting the'photograph for distortion introduced due to the fact-that the optical plane of the aero-camera 'lens was' not parallel to the eartlis surface at caused by the aero-lens axis not being per-pl pendicular to a horizontal plane at the moment of exposure, measuring the actual spatial positions of physical features relavtively to each other, sketching on the photo? graph topographical designations in correct arrangeiiientrelative to feature oints'ap-` caring onthe photograph, and tlientranserring the desired data to a separate sheet. 32. The improved .method of indicating topography which consists in obtaining an yaero-photograph covering a particular area, making the photograph of uniform scale and then sketching topographical indicia thereon Vaccording to observation of the measured actual. location of physicalfeaturedenoted thereby. 1

33. The herein describedmethod of visually indicating the character of anarea of the earths surface, that consists in marking on an aero-photograph of the particular area andy in their apparent relative positions toponoting topogra hical features.

34. The herein desribed methodof visually indicating the-topographical character of an area of the. earths surface, that con sists in tracing on topographical designations in their apparent location each to each on an aero-photograph of said area, and then transferring the, available data in true relationship upon'a separate surface according to survey-ascertained ratios of displacement.

. 'area of the earths surface, that consists in 'drawing contour lines on a uniform-scale the moment 4the image of the particular` graphical [designations of different kinds de-` aero-photograph 4of the particular area 4in their apparent relative positions' by direct observation and measurement of elevation variations, and then pantographing said contour lines in true relationship on map material. r

36. F or\use in the art of making a topographical map, the method of adjusting the relative locations of topographical symbols denoting physical features ofthe terrain,

which consists in marking topographical designations on ya photograph according to the apparent location of physical features disclosed thereon and vthen pantogra hing on a separate sheet a reproduction o said designations according to a pantograph setting involving the factor of `the correcting 'ratio' required due to the displacement of said photographed features in consequence of terrain relief.

37.. For use iii the art of makinga topographical map, the method of adjusting the relative locations' of topographical symbols denoting physical features of the terrain,

which consists in platting topographical des-- ignatious according to the apparent location of physical features'denoted by saidi designations as revealed by reference to a photographl of the area to be mapped, using a prepared chart t'ol determine the values of the adjusting factors of a pantograph according to. predetermined ratios required for correcting photographic displacement of theimages of said physical features, and then transferring to a separate sheet by use of'a pantograph so adjusted.A

38. Theuse in theart of making a topographical map, of the' method of adjusting the relative locations of topographical symbols denotingphysical features of the terrain, which consists in platting a plurality of topographical designations which are the determinant-sof a plane geometric ligure ac'- cording to the' apparent location of physical features denoted by said designations as refv yealed by reference to a photograph of the area ccmprehending said features, and then, with knowledge of the dimensions and ans gular nrelationof two sides of theoriginal plane ligure and according to the ascertained ring a. reproduction of said symbols so that they determine a different plane figure.

39. In the art of making a topographical map, themethod of adjusting the relative locations of topographical designations de- 1,15 actual elevations of said features ,transfer l noting physical features'of the terrain,v

lwhich consists in marking a photograh of .the Vparticular squares, select-ing four points onsaid phototerrain with coor inate graph,'determining the dimensions and angular relationship of twio sides of the plane geometric figure of which lsaid Apoints arethedeterminants, Iproviding a 'l chart suppliii with coordinate values denoting settings for two arms-of a pantograph and further sup-l ical map which consists in making anaero-v vphotograph, making the component parts of plied with 'a diagonal value/denoting the dimension of'fsaid coordinate squares, ascertaining thecorrection ratios required to shift the collective disposition of saidpoints fromv their displaced photographic positions due to varying terrain relief, determining and establishing the setting for the two arms of a pantograpli according to said ascertained correcting ratios and finally pantographing the four points to their correct actual relative positions as distinguished` from 'their incpli'rect photographically apparent relations 1 .4%. The step in an improved method of visually indicating the topographical character of an area, which consistsl in sketching on an aero-photo ent kinds and in their apparent relative positions as determined by visual recognition l desired, sketching.topographical "designations which denote existing physical features on the photographed terrain, and then pantographing transferring said designations to map material on an increasing ordecreasingratio according as the .elevation= of each particular hysical feature is learned to be above or low an arbitrarily chosen datum plane.` 42. The method of making a topographie'si'red, correcting the photograph by maksketching, thereon ytopographical designations which '-denote existing physical features on the photographed terrain, and then said designations to map material on a ratiowhicli is the functon of the `scale of an horizontal datum plane, of the vertical location of the Acontour with respect tosaid plane and of the scale desired for the map.

43. A. chart for use in determining the ratios of requiredl adjustment of control points on an aero hotograph, comprising coordinate valuesi enoting elevations, and a. diagonal line.

44. A hart for use correcting for the "displacement duev tio-ground reliefofa plurality of selected control points disclosed, on

' an -aero hotogra h, comprisingtright-angularly lre ated sca es of values denoting elevations-and used for determining coordinate lpantograpli settings, and a lineextending" vdiagonally across the chart and itself di- *vided by lines denoting a. linear. scale for determination of la grid dimension.

aph-of said areaconventional'topographical designations of differfeatures are denoted by said rilesigna-i 45. The method' of making a topographsaid photograph of uniform scale, ,selecting four fpoints on the photograph, determining by vground survey the location of said points relative to each other and relative to a selected datum plane, adjusting the relative location of said points according to their ascertained elevation with reference to the selected datum plane vand sketching on the photograph topographical designations denoting the feature points and contours and l lfinally transferring onto map paper on an increasing or decreasing ratio according to` the elevation of the physical features 'denoted by said designations. e

46.v The method of mak'ng a topograph-j i ical map which consists in taking an over-" lapping series of aerophotogr'aplis, selecting a plurality' of feature points on each, determining by standard survey practice the .location of said points relative to eachother'and relative to a chosen horizontal or datum plane, -determining the scale 'of the. picture including the step of platting the points,lv

locating thecenter of saidfpicture, transferring such center to its proper place between said selected points, scaling the distances from the determined center'to each of the selected points, multiplying each distance by the difference between the elevations of the datum plane and each one of the selected points respectively, dividing each of the products ,by the altitude at which the aero-- photographs were taken, laying off the quotients so obtained by measurement from the center of the plat, correcting the photo.

graphs to obtain pictures of uniform scale, coordinating the pictures into plane geometric figures, recording directly on thepliotogra hs the feature oints and contours 'and graphs as a .continuous series onto map paper to obtain tlie proper relative location of the topogra hical designations.

47. `Ametho of makingmaps which consists in obtaining for use a single aerophotog'raph ofA each particular area to be mapped, directly locating by observation of the terrain area itself, and recording per-v tinentl data relative to, terrain map points nallypantogfrap ing all lthe photo' iis as actually disclosed, and then constructing substantiallyV uniform scale.v

T48. A meth d of Vmaking atopograpliic with the aid of said recordations a map of map by use of a 'series of overlapping aerophotographs, whichv consists in using a single `aerophoto'graph of each particular portion of the varea. `to be mapped, directly locating by 4observation of the a-hctual area, andrecording pertinent data relative ,.to, terrain i map points as actually disclosed, and then constructing with'theaidof said recordations a map of substantially uniform scale and coinpr'ehending the recorded data of the used portions of all of theaerophotographs.

49. The method of correcting the dislaccording to their calculated displacement caused by the 'perspective factor due to terrain relief and then drafting a map dc-picting the map points so shifted.

50. A method of making a map which consists in obtaining an aerophotograph ofthe area to be mapped, identifying inap points on the terrain by coinpaiison with their images onLsaid photograph, recording the real relative locations of said map points and vthen drafting a map with the photographically apparent positions of said map points adjusted toand depicted in their correct relative locations.

51. A method of making a topographical map which consists in obtaining an aci-ophoence to images thereof as disclosed' on saidA 'tograph of the Yarea to be mapped, identify- -ing real physical features, contemplated for use as inap points and constituting data customarily used in drafting a map, by lreferphotograph, estimating'and recording the` topographical locations of said map points,v

and then drafting a uniform scale map by adjusting the photographically apparent relative locations of said' map points to their' true relative locations' with reference to a cations vof photographic images of physical chosen substantially horizontal datum plane. `52. In the art of making a topographical inap,the method of adjusting the relative lofeatures of the terrain, which consists iii markin, ,er a photograph of the particular tei'- rain with a plane geometric g'ure,'selecting four lpoints on s aid photograph three of' 'ordin'a-te values. denoting settingsy for tWoarmsof a pantograph and further supplied With a diagonal valuel denoting dimensions ofsaid plane figure, ascertaining the correcvtioiiratios required -toshift the collective disposition of said points from their displaced photographic positions due tol var ning terrain relief, determining and-establis 1- ing the setting for the two'arms of a panto- ,grgaph according to said ascertained correcting ratios, pantotgraphing the four points to their correct 'actual relative positions as dis'- tingu'ished from their incorrect photographically apparent relationship andfinally supplying topographical designations in'accordanc-e with the ascertained ratios of displacement.

53. The method of making a topographical map which consists in obtaining aeropliotographic records of the terrain of whichL a inap is desired, sketching thereon topographical designations which denote by cinphasis and amplification physical features on the pliotogral'ihed terrain, and then transferring said designations to map material in such aivay that the variance in relative locations of thedesignations on the aerophotographic records with respect to those as' transferred onthe map material is a function ot' thealttudc of the aerophotographic recorder above an assumed .datum plane, the

focal length of the lensr of the aerocaiuera, and the positions ol the designations with respect bolli to the ground point in the lens axis and the point vertically below the. lens at exposiu'e and the sca-le for the linishedv inap.

54.' A method oi" making a map which consists in obtaining an :ierophotograph of the area to be. mapped, identifying inap points on the terrain by comparison with their images on the said photograph, determining the elevati-ons of said inap points, and then making a inap by drafting disclosures of the photograph and therelative .elevations as .above determined.

55. The steps in the art of making a topographical map which consists in deter- .niining the actual location of any desired inap point hy `identification of the image-ol the physical feature .denoted by said map point on a singlev photograph and by observation and ascertamment ot its 4true elevation and then recordlng a topographical des- I ignation of said inap point shifted'fron'i its photographically apparent position -to its correct position with respect to any chosen datum plane.`

5 6. The art of making'a topographical map.l which consists in obtaining an` aerophotograph of the'terrain to be mapped, altering the apparent relative locations of map points disclosed by said photograph by eliminating elenie'nts of horizontal perspective partially to correct the photograph, determiningthe actual location of any map'point byidentiiication of the physical feature corresponding to it on `said 'correctedjpl'iotograph and byobservation andascert-ainment of its true'elevation" and, vthjen recording a A"topogzlrapliical' designation of' said mapy point additionally'ishifted in position "relative to other inappoints. 'i

57; ,"llhe steps in the method of making a topog'lllliiical inap which consistsin obtaining anaeophotograph, ascertaining the actual elevation of a desiredmap point a pearing on ysaid photograph, ascertaining t ie photographical displacement of said ,map

pointv in consequence of'it's` difference in ele-` tion.

vat-ion with respect to othei map points and then recording a topographical designation of said map point shifted to its correct posi- 58. The method -of making a topographical map which consists in, identifying map points by reference to an aerophotograph'of the terrain to' be mapped, ascertaining the approximate elevation of desired map points, determining the calculated photographical displacement of said map points in conseuence of their respective elevations and tien recording topographical vdesignations of said map points shifted totheir correct respective elevations relative to a chosen calculating the photographical displacement of said map polnts in consequence of their datum' plane, recording on said photograph vtopographical' designations -of said map points shifted to their correct vposition relatively to each other'and finally transferring to a'map sheet all the desired `map points in Y photograph of the terrain of which a map is "graphical mapv their correct .relative positions.

60. The steps in the art of'making a topowhich consists in obtaining an aerophotograph of the terrain of which' a map is desired, and recording a shifted location of 'anyl once photographically re' corded mapv point according to its 'ascertained elevation with reference to an adopted 'datum plane.

61. The art of 4makin altopograhpical map which consists in o tainngan aerodesired,'and shifting the relative location of desired map pointsaccording to their differing'elevations with reference to an' adppted datum plane while transferring to vmap aper. Y 62.- The art of makin atppograph-ical map which consists in o taining an aerohoto raph of the terrain of which a map is esire altering the relative locations ofv map points 'by rephotographyto. eliminate elements of horizontal pers ective inconsequcnceof an incl'nednptic'a axis at the -mo'- ment said photograph was obtained, and additionally shiftin fthe Vlocation-gf a desired` map point accor ing to its ascertained elevation with-'reference to an adopted datum;

plane'by transference'to map paper.

' 63. )The method of making 'a topogra hiicalmap by draftingy map points accor ing to the true relative locationsof ysical features of... the desiredterrain alle placement of physical :elements of horizontal perspective iii' said denoting said features from single aero- I photographed images of the latter.

64Y The method ofmaking a topographi-vv cal map by drafting map'p'oints 'whichdenote physical features of the terrain of which a map is desired according to the shifted'relative locations of said features as disclosed by an aerophotograph which has been corrected by the elimination of all elements of l perspective. A

65. The method of making a topographical map which consists in obtaining an areopliotograph of the terrain of which a map is desired, eliminating elements' of horizontal perspective from said photograph, eliminating elements of vertical perspective in said photograph, said elimination procedures determining relocations of said physical featurcs relatively to each other and then drafting a map 4having.topographical designationsdenoting map' points coresponding to said physical features and arranged in correctrelation to each other with reference to a particular chosen datum plane and a desired scale.

,66. The method of making a topographical inap which consists in obtaining an aerophotograph which are distorted in consequence of ele- 'ments of horizontal lperspective in said ho.- tograph, by recording appropriate in icia thereof, relocating physical features, which are displaced in consequence of elements of vertical perspective 1n said photagraph, by recording appropriate indicia .thereofand of the terrain of which a map- 1sdesired, Arelocating physical features,l

nioV

then drafting a map having topographical designations denoting map points corresponding to said physical .features-andar,- rangedv incorrect re1ation to `each other with reference to a chosendatum plane,

andaccording to a desired scale.

67. The method of-fmaking a topographical map 'which consists in obtaining an aerophotograph of the terrain of which a mas is desired, ascertaining the photograp'hical iseatures because of photogra h due to 4an inclined y optical axis whensai photogra h was obtained, recordits' ing ,appropriate indicia thereof in 'positions altered according to said ascertainment, ascertainingthe photo raphical displacement'v of physical features;- ecau'se of elements of vertical pers ectiye in said photograph. dueto terrain -re ief, .recording` appropriate indiciathereof inposit-ions altered according to said.; second' ascertainni'ent-,. andA then dra ting a map having topographical designations denoting map points corresponding to said physica features -and-arrangedfin correctrelation to eachother subject to an application of'sa-id ascertainments.

68. The'method of making a topographi-l cal map which consists in obtaining a'n"' aero'4 tures comprehended by saidp telligence furnished ther'eb by recording map points, contours and ot ier topographi-- cal data. aided by a determination of the actual .location and character 'of Ehysi'cal fea.-

'otograph 69. The method of making a topographical map which consists in obtainin anaerophtograph of the terrain of whic 'a topographlcalmap is desired, correlatin -the mtelllgence furnished thereby by s etching map points; contours, and other topographical data aided by a determination of the re1- ativc locations and elevations o f ph sical features of the terrain disclosed bysai photograph and then drafting a comprehensive .map correctly showing all of the desired information.

Signedby us, 1922.

EDWIN H.v CORLE'IT. MAX W. GARNETT. y HOWARD I. DOREMUS.

this first day of September, 20 

